[OPTICAL REVIEW Vol. 6, No. 6 (1999) 494-496]

Influence of Nonlinear Gain Saturation on the Time-Bandwidth Product of Optical Pulse from a Gain-Switched Semiconductor Laser

Kenji WADA,1 Tetsuya MATSUYAMA,1 Hiromichi HORINAKA1 and Yoshio CHO2

1Department of Physics and Electronics, Faculty of Engineering, Osaka Prefecture University, Gakuen-cho 1-1, Sakai, Osaka, 599-8531 Japan, 2Oyokoden Applied Photonics Lab Co., Ltd., 5301, Haga, Okayama, Okayama, 701-1296 Japan

(Received April 26, 1999; Accepted September 2, 1999)

It is found numerically that the time-bandwidth product (TBP) of optical pulse from a gain-switched semiconductor laser operating under a sufficient gain saturation condition increases monotonously with increasing modulation amplitude. This enhancement of the TBP becomes remarkable for longer-wavelength semiconductor lasers (1.3, 1.55 μm) having large value of the gain compression factor ε (~10−23 m3), making the pulse chirp estimation using the TBP difficult.

Key words : semiconductor laser, gain saturation, time-bandwidth product, pulse chirp estimation, gain-switching